Sheldon Cooper has a PhD in Physics and knows the importance of a good prank. Executing a good prank takes skill, prowess, agility and patience. Patience is the key for proper use of the term "Bazinga". Here are some typical scenarios for use of the term "Bazinga":

When your friend gets drenched in water after waking into a room -> Bazinga!

When a coworker tries to eat your sandwich but finds the peanut butter was swapped with sawdust -> Bazinga!

When your brother thinks it's Monday and goes to school on a Saturday -> Bazinga!